Apparatus for treating chemicals



July 13, 1943. w. A. CARLSON ETAL APPARATUS FOR TREATING CHEMICALSjjvenzozu JcVaZZer A. on,

Carla Filed Aug. 3, 1940 d M 13,1943 Y 2,324,195

UNITED STATES PATENT OFFICE 2,324,195 APPARATUS FOR TREATING CHEMICALSWalter A. Carlson and Paul W. Salo, Minneapolis, Minn, assignors toGeneral Mills, Inc., a corporation oi Delaware Application August3,1940, Serial No. 351,0zo

. 6 Claims. (Cl. 23-267) V This invention relates to apparatus fortreatare substantially all retained by the cloth and ing chemicals andmore particularly to apparathe'screen. ,n.

tus for rapidly dissolving a chemical to be purl- The upper end of therod connects through a iled in a hot solvent, recovering the volatilizedsuitable connecting rod 28 with a crank pin 26 on solvent andrecrystallizing under conditions oi j controlled cooling.

a plate 21 which is rotated at a suitable speed v through a reductiongearing, not shown, by An object 01' the invention is to provide asimmeans of a motor 28.

ple and eflicient apparatus of this type for the Thus the containersecured to the bottom 01" purification of crystalline chemicals and forthe the rod II acts as an agitator when moved up recovery of theirsolvents. and down by the connecting rod 25 and greatly Another objectis the provision of a process for increases the rate of solution of thechemical A dissolvinga chemical and for recovering the same in thesolvent B in the kettle. This solvent is in crystalline form underconditions which first purposely kept well below the top 01' the kettlecause rapid solution without the application of so as to'leave a clearspace 30 into which the sumcient heat to injure delicate chemicals, suchfilter member can be raisedas shown in dotted .as those containingpro-vitamins like ergosterol, lines. A suitable chain and hook 3i arepro and then bringing about recrystallization of that videdfor fasteningthe'rod in the elevated posichemical in the same apparatus under themost -tion so asto permit the filter 20 to be raised favorableconditions. to the dotted position in which the residual sol- These andother objects as will hereinafter 20 vent may drain therefrom. appearare accomplished in this invention which A pipe sit-supplied with avalve 34 connects is fully described inthe following specification withthe. bottom of the jacket II and serves as and shown inthe accompanyingdrawing in -a drain. The jacket also connects through a which horizontalpipe 35 with a vertical pipe 38 which Figure l is a vertical sectionthrough the 'apin turn connects through a valve 31, a cylinder paratus;I l8 and a pipe 39 with the top of the Jacket. An Fig. 2 is a partialend elevation oi the motor for expansion tank .40 connects through apipe 4i agitating; v with the top of the jacket and has an overflow Fig.3 is a perspective view of a perforated conpipe 42. A pipe 43' having avalve 44 leads down ,tainer for holding the materialt'obe treated; fromthe pipe and connects with the water Fig. 4 is a partial enlargedsection on the line supply. A coil 45 is located in the cylinder II 4 ofFig. ii; and I and has pipes 46,41 by means 01 which hot or is it 17enlarged perspective View cold liquids or steam may be circulatedthrough 322 g g sg i fig gg gg a otb Q t d the coil fcgr heating orcooling the water in the cylinder 3 A pipe 48 controlled by a valve 48vemlgodiment illustrated comprises kettle is connected to a suitablesource of steam and g ifg i $2 1 3: 2 522 gz gt fifiz is provided withan injector 50 for heating Jacket ii surrounded by a heat insulatingjacket fi ggg i gignzzgfig ggd 12 3x63 duii gg l2 and provided with aheat insulated cover i3 the heating cycle. which is secured thereto asby means of bolts l4. a

A rod i5 preferably extends through the cover gg g g g zg gi gg ffi fiigs and is provided with a suitable packing gland ii. y a y This rodcarries series of arms terminating valve it, one side 01' th valveconnecting through in anus m A fine wire screen '9 is soldered a pipe,"with a receiver 58 and the bottom to to this ring so as to completelyclose the same is provided vent and prevent the passage or the materialto be 88'. For convenience, a thermometer 59 isprotreated past thescreen. A cloth cover 20 de- 9 887mm the temperature M the jacket pendsfrom the ring it to which it is secured by H d a th m the temperaturemeans oi a band II, the ends of which are- 9 the q t drawn together byany suitable form of clamp Y A e-5 leads r the space 30 above the '22.The mat rial A t be t e 1 m with; liquid in the kettle to a condenser 60and thence this cloth which serves as both a containerand through a.sight box 61 to a re eiver Bl which is a filter since the material to bedissolved and provided witha vent. 88.. A coil 89 in thcylrecrystallized often contains impurities. These 66 Rider 4 issupplied with cold water through a pipe Ill, the water being carried toa drain through a pipe 'H.

Thus it will be" seen that the solvent B in the kettle vaporizes andpasses over through the cooling coil 89 where it is condensed and passesinto the receiver as as recovered solvent C. This receiver is drained bymeans of a pipe 15 which connects through a valve with a hand pump 11the delivery side of which connects through a pipe 18 with a pipe 35.The intake of the pump 11 also connects through a valve 19 and a pipe 80with the bottom of the receiver 58. The receiver 58 may also be drainedby means of a valve 8!, and the receiver as may be drained by a valve.2.

Thus the recovered and purified solvent C in the'receiver 68 may bereturnedto the kettle by opening the valve 18 while the valve 19 remainsclosed. On the other hand, the liquid D in the receiver 58 is theunvaporized residue which has been drained from the kettle and this maybe returned to the kettle if desired by opening the valve 19 while thevalve It remains closed by the operation of the pump 11.

It will be apparent that by means of the kettle and its associatedparts; the operator has a piece of apparatus by which he can perform amultiplicity of operations and control the speed of those operations toa very high degree.

Thus he takes a material like ergosterol which contains impurities andplaces them within. the filter bag at the bottom of the agitator. Hethen tightly clamps the cover on the kettle and heats the water withinthe jacket Ii by means of steam from the pipe 48 and proceeds to agitatethe filter assembly 20 in the solvent B. During this operation some ofthe solvent may boil of! in which case it is cooled by the coil 69 andfalls into the receiver 68. This operation then continues until theergosterol or other chemical is sufllciently dissolved in the solventafter which the cloth bag is raised to the dotted line position ofFigure l and permitted to drain into the kettle. This operationconstitutes an instantaneous hot filtration, and eliminates a jacketedpump and pipes normally required, as well as a second tank needed as areceiver after filtration.

Cooling the liquid B will now cause the dissolved ergosterol torecrystallize on the walls of the kettle. The rapidity with which thisoccurs will depend very largely on the rapidity of cooling this liquid.If all of the valves 34, 31 and 44 are closed, the water in the jacketwill cool but slowly, due to the efiiciency of the heat insulation I2.If, however, it is desired that the rate of cooling be accelerated, theoperator will open the valve 31 and a thermosyphon action will takeplace which .will greatly increase the rate of cooling due to the factthat the cylinder 38 is not heat insulated. Should he wish to increasethe rate still further, cooling water is allowed to circulate throughcoil 45. This accelerates the thermosyphon and yet gives good control ofthe cooling rate. By this method, there are no large local difierencesin temperature in the jacket. A greater increased cooling rate may beobtained by admitting cold water to valve 44, the hot water overflowingthrough the expansion tank. When cooling is done by this method, thereis an abrupt change in temperature as the level of the cooling watergradually rises from the intake valve and finally reaches the expansiontank.

Thus it will be seen that a very eflicient and self-contained apparatusis provided for the recovery of certain chemicals in purifiedcrystalline form; the operator is enabled to control the rate ofsolution and recrystallization to a very high degree in addition tocarrying out such usual operations a recovery of solvent.

After the mother liquor has been drawn oi! through the valve 58, thecrystals deposited on the walls of the kettle may be washed with anysuitable liquid such as a small'amount of the purified solvent C inreceiver 08 which may be forced into the kettle by the pump 11 and thendrained of! by the valve 56. These crystals may then be removed from thekettle and spread out to dry.

This type of apparatus has been found very I useful for purifying suchmaterials as ergosterol as described in the example. It is alsosimilarly useful for extraction of drugs and other chemicals from a massconsisting of unimportant insoluble or partly soluble material. At timeswhen the apparatus is used for such purpose, it is naturally convenientto carry out a simultaneous crystallization of the extracted material.If the extraction has been carried out with hot solvent, it will oftenbe possible to crystallize merely upon cooling the solvent. At othertimes, it will be found necessary to distill off part of the solventafter extraction has been completed and then crystallize the productfrom the resulting concentrated solution. It is also obvious thatsolvent recovery may be carried out in the apparatus as a separateoperation to provide fresh solvent for future extractions. This andother variations of the use of the equipment would be obvious to theoperator.

Depending upon the size and construction of the equipment, some of thedetails of construction can be varied considerably; for example: insteadof having a removable cover, it is possible to have a completelyenclosed tank to which access is allowed by means of a manhole; aftereach operation, the product can be removed and new material introducedthrough such an opening.

Similarly the water Jacket may be replaced by a steam jacket or by meansof hot air as desired. However, in such a case one loses the advantagesof the thermosyphon method of controllingthe rate of cooling.

We claim as our invention:

1. Apparatus of the class described comprising a kettle having a jacketfor holding a heat exchange medium, a closure for the kettle, a

porous container constructed to hold a substance, to be treated withinthe kettle, supporting for the container extending through the closure,driving means connected to the supporting means for reciprocating thecontainer through a predetermined path within the kettle, andmeansassociated with the supporting means for lifting and maintaining thecontainer above said path.

2. Apparatus of the class described. comprising a kettle having a jacketfor holding a heat exchange medium, a closure for the kettle, a porouscontainer constructed to hold a substance to be treated within thekettle, supporting means for the container extending through theclosure, driving means connected to the supporting means forreciprocating the container through a predetermined path within thekettle. means associated with the supporting means for lifting andmaintaining the container above said path, piping connected to the topandbottom portions of the kettle jacket, and said piping having meansfor introducing, withdrawing and circulating the for the containerextending heat exchange medium within jacket.

3. Apparatus of the class described comprising a kettle having a Jacketfor holding a heat exchange medium, a closure for the kettle, a porouscontainer constructed to hold a substance to be treated within thekettle, supporting means for the container extending through theclosure, driving means connected to the supporting means forreciprocating the container through a predetermined path within thekettle, means associated with the supporting means for lifting andmaintaining the container above said path, piping connecting the top andbottom portions of the kettle Jacket, and valve means in said piping forcontrolling the flow of the heat exchange medium therethrough.

4. Apparatus of the the piping and class described comprising a kettlehaving a jacket for holding a heat exchange medium, a closure for thekettle, a porous container constructed to hold a substance to be treatedwithin the kettle, supporting means for the container extending throughthe closure,

driving means connected to the supporting means for reciprocating thecontainer through a predetermined path within the kettle', meansassociated with the supporting means for lifting and maintaining thecontainer above saidpath, piping connecting the top and bottom portionsof the kettle Jacket, said piping having means for circulating andcontrolling the flow of the heat exchange medium within the Jacket, andmeans associated with the piping for varying the temperature of the heatexchange medium therein.

5. Apparatus of the class described comprisexchange medium, for thekettle. a porous container constructed to hold a substance to be treatedwithin the kettle, supporting means through the closure, driving meansconnected to the supporting means for reciprocating the containerthrough a predetermined path within the kettle, means associated withthe supporting means for lifting and maintaining the container abovesaid path, piping connected to an upper portion of the kettle forwithdrawing vapors therefrom, condensing and collecting means connectedto said piping, means connected to a bottom portion of the kettie forwithdrawing and collecting liquid thererom, and a pump having pipingconnected to each of said collecting means and to the kettle forreturning liquid to the kettle.

' 6. Apparatus of the class described comprising a kettle having ajacket for holding a heat exchange medium, a closure for the kettle, aporouscontainer constructed to hold a substance to be treated within thekettle, supporting means for the container extending through theclosure, driving means connected to the supporting means forreciprocating the container through a predetermined path within thekettle, means associated with the supporting means for lifting andmaintaining the container above said path, pipingconnected to an upperportion of the kettle for withdrawing vapors therefrom, condensing andcollecting means connected to said piping, means connected to a bottomportion of the kettle for withdrawing and collecting liquid therefrom, apump having piping connected to each of said collecting means and to thekettle for returning liquid to the kettle, other piping con-- nectingthe top and bottom portions of the kettle jacket, said other pipinghaving means for circulating and controlling the flow of heat exchangemedium within the jacket, and means associated with said other pipingfor varying the temperature oi the heat exchange medium therein.

WALTER A. CARLSON. PAUL W. SALO.

